Forging or upsetting of metal rods or bars using electric resistance heating



June 14, 1949. M. o. HANNA 2,473,245

FORGING 0R UPSETTING OF METAL RODS 0R BARS USING ELECTRIC RESISTANCE HEATING Filed May 2, 1946 2 Sheets-Sheet l llillfi nztmu. Qhver HANN A \N NTom June 14, 1949. M. o. HANNA 2,473,245

FORGING OR UPSETTING OF METAL RODS 0R BARS USING ELECTRIC RESISTANCE HEATING Filed May 2, 1946 2 Sheets-Sheet 2 ,I MERRILLOHVEK HAN NA \NVE N TOP- Patented June 14, 1949 FORGING R UPSETTING OF METAL RODS 0R BARS USING ELECTRIC RESISTANCE HEATING Merrill Oliver Hanna, Darebin, Victoria, Australia Application May 2, 1946, Serial No. 666,581 In Australia May 26, 1945 4 Claims.

double-ended articles or tools such as spanners or the like, and a specially constructed apparatus for carrying out such method of manufacture.

According to the invention, spanners or doubleended articles or tools are manufactured from metal rods or bars by heating their opposite end portions to forging temperature by passing a heavy current of low voltage through such end portions and applying endwise pressure to the metal rod or bar to cause the metal at such heated ends to flow or be upset to form substan-- tially bulbous portions which subsequently form the enlarged ends of the spanner or tool.

After the bulbous portions have been formed, the current can then be passed through the full length of the metal rod or bar to heat the whole of such rod or bar to forging temperature so that it can be delivered directly to a drop forging or like machine for shaping to the final shape of the spanner or the like.

The heating current is applied to the end portions of the rod or bar through end contacts, which also apply the endwise forging or upsetting pressure, and intermediate or gripping contacts which are arranged to engage the rod or bar at an approved distance from the end. Preferably, the intermediate contacts are connected together in series to that the same current passes through both end portions of the rod or bar and substantially uniform heating will thus take place at both ends of the rod or bar.

The invention is more fully described aided by reference to the accompanying drawings where- Fig. 1 is a diagrammatic View showing the rod or bar in position between the end or pressure applying contacts and the intermediate or gripping contacts with the current flowing between said contacts through the end portions of the rod or bar to heat such portions to forging temperature.

Fig. 2 is a similar View to Fig. l, but showing the pressure applied by the end contacts causing the metal of the heated end portions of the rod or bar to flow or be upset to form the bulbous portions.

Fig. 3 is a similar view to Fig. 2, but showing the upsetting operation completed and the intermediate or gripping contacts withdrawn from the rod or bar with the current now flowing through the full length of the rod or bar to heat the whole of said rod or bar to forging temperature.

Fig. 4 is a view of the doubly upset rod or bar as produced.

Fig. 5 is a front elevation of the apparatus as used for carrying out the improved method.

Fig. 6 is a plan view of Fig. 5.

Fig. '7 is a diagrammatic view illustrating a modification.

As shown in these views, I indicates the metal rod or bar, 2 the end or pressure-applying contacts and 3 the intermediate or gripping contacts which are arranged to engage the rod or bar at approved distances from its opposite ends. Such distance can be governed by known factors in the art of upsetting.

The intermediate contacts 3 are adapted to be moved into and out of contact with the rod or bar 1 and, for such purpose, they may be connected to fluid-pressure actuators 4 or equivalent means.

The end contacts 2 may be both movable to apply endwise pressure to the rod or bar I but preferably one contact is stationary while the other is movable as by means of a fluid-pressure actuator 5 or other appropriate means.

The end contacts 2 are connected by leads 6 to a source of heavy low voltage current such as the secondary winding 7 of a step-down transformer 3, the primary winding 9 of which is connected to a suitable electric supply.

The intermediate or gripping contacts 3 are coupled together in series by means of a bridging connection H).

In use, the rod or bar i is placed or fed to position and gripped by the two end contacts 2 and the intermediate contacts 3 which are moved inwardly by means of their actuators 5 and 4. Current is then supplied and passes from one end contact 2 through the end portion of the rod or bar to the first intermediate or gripping contact 3 and thence via the bridging connection In through the other contact 3 and other end of the bar or rod to the other end contact 2, see arrows in Fig. 1. The opposite end portions of the rod or bar are thus heated and when such end portions have become heated to forging temperature, the pressure of the end contacts 2 causes the metal of said heated end portions to flow o1 become upset as shown in Fig. 2 to form the bulbous portions I! which subsequently form the enlarged ends of the spanner or tool produced from the rod or bar I.

When the metal has been upset to the desired extent, the intermediate or gripping contacts 3 by known means.

are withdrawn from the rod or bar by means of their actuators 4. This removes the bridging connection l and the current now flows through the full length of the rod or bar between the end contacts 2 as shown by the arrows in Fig. 3 and the whole of the rod or bar is now heated to forging-temperature for delivery directly to a drop forging or like machine which forms the heated rod or bar to the final shape of the spanner or tool.

The bulbous or upset portions H provide sufficient metal to form the enlarged ends or heads of the spanner while the central portion of the rod or bar forms the stem or shank portion of the spanner.

To enable the rod or bar to be conveniently handled, if required, when in heated state, a tong hold 12 may be provided at one end. This can be conveniently produced by providing a hole l3 in one of the end contacts 2 to enable one end of the rod or'bar to be enclosed. The upsetting of the metal at that end of the rod or bar then takes place adjacent to said tong hold as shown .fixed'relationship toeach other on slides [4 arranged to slide on rods I5 or the like on the base "Hiof the apparatus. The contacts are, of course, .suitably insulated electrically from each other and also from the slide.

The actuators 4 for the contacts 3 are preferably also carried from such slides.

'By this construction, the distance between the contacts 2 and 3 remains constant during the upsettingoperation and, as the movable contact 2 moves inwardly and the rod or bar I shortens,

thecontacts 3 slide along the rod or bar in uni- "son with the contact 2.

This maintains opti mum upsetting conditions and also enables practically any desired quantity of metal of the rod 'or bar tobe upset into the bulbous portions H within,'of course, reasonable limits.

'If desired, the contacts 2 may be constructed with receding heads of well-known construction.

The apparatus can be automatically controlled Thus, when the end portions of the rod or bar have been heated to the desired forging temperature, the actuator 5 for the'end contact 2 can be brought in operation automatically by means of suitable temperature controls. Likewise, when the rod or bar has been upset to the desired extent, the actuators 4 can come into operation automatically to withdraw the *contacts 3 and permit heating of the full length of the bar or rod. Again, when the whole rod or bar has been heated to the desired forging temperature, temperature controlled means may come :into operation to eject the heated rod or bar from the apparatus and deliver it to the forging machine.

In a modification of the invention, the central portion of the rod or bar I may be given a preliminary heating, not sufficient to brin it to a plastic state, during the time the end portions are of, the central part of the rod or bar.

The preliminary heating of the central porztion-of .the rod is effected by causing a portion ofcthe current to leak or pass through the cen- '4 tral portion of the rod or bar during the heating of the end portions. This is done by inserting a resistance as I! in the bridging connection It! as shown in Fig. 7.

By the method of manufacture and apparatus as described, spanners and like double-ended tools can" beamanufacturedmore expeditiously and economically'than by existing methods of manufacture.

What I claim is:

1. A method of manufacturing spanners or double-ended articles or tools which consists in heating the-opposite end portions of a metal rod or bar to forging temperature by passing a heavy current of low voltage through said end portions, applying endwise pressure to the metal rod or bar to cause the metal at such heated ends to flow or be upset to form substantially bulbous portions which subsequently form the enlarged ends of the spanner or tool, giving the central portion'of the rod or bar a preliminary heating, not sufiicient to bring it to a plastic state, during the time the end portions are being heated and upset .by causing a portion of the current toleak orpass through said central portion, and finally passing current through the full length of the rod orbar to heat the-whole of said rod orbarto. forging temperature.

2-. An apparatusfor manufacturing spanners or double-ended articles .ortools comprising end contacts to engage .the opposite ends of a rod or bar to supply the heating current and apply the upsetting pressure and. intermediate contacts adapted-to engage the rod or bar at spaced distances from the. .end contacts, said intermediate contacts being connected together in series so that, when they are engaging the metal rodor .bar, vthe heating current passes through the end portions only of such rod or bar to heat suchportions .and, when said intermediate contacts .arewithdrawn from the rod or bar, theheating current passes through the fullv length of the rod or bar to heat the whole of same.

3. An apparatus as .claimed in claim 2 wherein the end contacts and intermediate contacts are maintained ata constant fixed distance apart during-the upsetting operation, the intermediate REFERENCES CITED The following referenlces are of record in the file of-this patent:

UNITED STATES PATENTS Number Name Date 483,424 Coflin Sept. 27, 1892 1,752,598 Jorgensen Apr. 11, 1930 1,849,185 Giacchino Mar. 15, 1932 1,867,936 Benedetto July 19,- 1932 7 2,006,459 Jones-ct a1 July 2, 1935 FOREIGN PATENTS Number Country Date "385,391 1 Germany Nov. 23, 1923 

